1. Field of the Invention
The present invention relates to an etchant, an etching method using the same, and a method for manufacturing a semiconductor substrate product.
2. Description of the Related Art
An integrated circuit is manufactured in multiple stages of various processing processes. Specifically, in the manufacturing process, deposition of various materials, lithography of a layer of which an entire portion or a necessary portion is exposed, or etching of the layer is repeated several times. Among these, the etching of a layer of a metal or a metal compound becomes to be an important process. A metal or the like is selectively etched and other layers are required to remain without corroding. In some cases, it is necessary that only a predetermined layer be removed in the form in which layers formed of similar metals and a layer with high corrodability remain. Wiring in a semiconductor substrate or the size of integrated circuits are becoming smaller and thus the importance of performing accurately etching on a member such that it remains without corroding has been increasing.
When an example of field effect transistors is considered, there has been a strong demand for thinning of a silicide layer to be formed on the upper surface of a source and drain region and development of new materials along with rapid miniaturization of field effect transistors. In a salicide process of forming the silicide layer, a part of a source region and a drain region formed of silicon and the like formed on a semiconductor substrate and a metal layer attached to the upper surface thereof are annealed. For a metal layer, tungsten (W), titanium (Ti), cobalt (Co), or nickel (Ni) is being used. In this manner, a silicide layer with low resistance can be formed on the upper side of a source and drain electrode or the like. Currently, in response to further miniaturization, formation of a NiPt silicide layer to which platinum (Pt) which is a noble metal is added has been suggested.
After the salicide process is performed, the metal layer remaining in the region is removed by etching. The etching is usually performed through wet etching and a mixed solution (aqua regia) of hydrochloric acid and nitric acid is used as a liquid chemical. WO2012/125401A discloses an example of using a liquid chemical to which toluenesulfonic acid is added in addition to nitric acid and hydrochloric acid.